The present relates to the field of the textile industry, particularly the treatment of threads using heat treatment machines generally known as heat setting machines, and relates to a sealing head for such machines.
These heat treatment machines comprise a pressurized chamber for heat treating textile threads laid on a conveyor belt traversing said chamber, which is closed at both its ends by sealing heads each comprising a frame fixed to the pressurized chamber, a pair of horizontal rollers placed on top of each other and pressed against the opposite faces of the conveyor belt and seals to form a sealed closure between the rollers and the frame.
At present, the horizontal rollers are actuated by tightening means that allow movement of at least one of the rollers in the direction of the other and the seals are in the form, on the one hand, of an upper element and a lower element extended and resting against the generators of the two rollers and, on the other hand, of side sealing plates resting in a sliding manner against the corresponding ends of the rollers.
The seals, both horizontal and vertical, are applied by means of actuators, in the form of high-pressure hydraulic cylinders, with drilled rods or cylinder blocks for the horizontal components and high-pressure hydraulic cylinders with angle return levers, for the side sealing plates. The drilled cylinder blocks are, in fact, cylinders with several pistons and piston rods that are aligned in parallel in a single cylinder block and have a single hydraulic supply, their operation being in addition identical to that of the usual hydraulic cylinders.
These known actuators, in the form of cylinders, provide an adequate response to the problems posed, on the one hand, of application under pressure of the horizontal rollers against the conveyor belt and, on the other hand, of the seals against said rollers.
However, due to their structure in the form of high-pressure hydraulic cylinders, that is operating at a pressure of approximately 80 bar, there is a risk of hydraulic liquid leaks that could lead to said liquid flowing over the rollers and/or onto the textile material and, as a corollary, the contamination thereof. It is therefore necessary to recycle the oil. It follows that the hydraulic device for applying pressure is subject to significant heating that could lead to a stoppage of the machine and the corresponding maintenance work.
In addition, because pressure is applied by means of hydraulic fluid, which cannot be compressed, the sealing head unit has a completely rigid system for applying pressure that allows no fluctuation or variation of pressure on any of the actuators.
Finally, because of the actual structure of the present sealing heads with actuators in the form of hydraulic cylinders, the maintenance work is relatively complex and long and leads to correspondingly long machine stoppages, which reduces their productivity.